French military forces on Monday widened their bombing campaign against Islamic extremists occupying northern Mali, launching airstrikes for the first time in central Mali to combat a new threat as the four-day-old offensive continued to grow.

Early Monday, an intelligence agent confirmed that shots rang out near the Diabaly military camp in what is still nominally government-held territory and that soon after, jets were heard overhead, followed by explosions. The agent insisted on anonymity because he is not authorized to speak publicly on the matter.

A Malian commander in the nearby town of Niono said the bombardments did not stop the Islamist fighters and that they occupied Alatona, and on Monday, they succeeded in reaching the north-south road which connects Diabaly to Segou, the administrative capital of central Mali.

By sweeping in from the west the al-Qaida-linked insurgents are now only 400 kilometers (250 miles) from Mali's capital, Bamako. Before France sent its forces in on Friday to stop a rebel advance, the closest known spot the Islamists were to the capital was 680 kilometers (420 miles) away, though they might have infiltrated closer than that.

Fighter jets late Sunday dropped bombs in the central rice-growing region of Alatona after a rebel convoy was spotted 40 kilometers (24 miles) southeast of Diabaly, until recently the site of a major, U.S.-funded Millenium Challenger Corporation project. The rebels, said a Malian commander in the nearby town of Niono, were trying to reach Diabaly, home to an important Malian military base.

The commander, a major, insisted on anonymity because he was not authorized to speak to the press.

French Defense Minister Jean-Yves Le Drian on Monday insisted that the situation in Mali "is evolving favorably." However, he acknowledged challenges in the west.